Learning from Mistakes: Failure to Re-start

Date of Accident: 12 September 2002 Time of Accident: 1043Z Aircraft Registration: ZS-KHG Type of Aircraft: Beech 76 Pilot-in-commandLicence type: Commercial Licence Valid: Yes Age: 40 Total Flying Hours: 1043.3 Hours on Type: 4.9 Last point of departure: Wonderboom Next point of intended landing: Wonderboom Location of the accident site: Approximately 7 nm NE of Wonderboom Meteorological Information: CAVOK, Wind NE at 8 Knots Number of people on board: 2+0 No. of people injured: 0 No. of people killed: 0

Synopsis

The student pilot was accompanied by an instructor to the Pretoria General Flying Training Area No. 2 for the completion of an initial twin conversion. Prior to the flight, the student was unable to start the Left-hand engine and had to obtain assistance from the nearby AMO. The dual magneto of the said engine was removed and bench tested and found to operate normally. After re-installation of the magneto, the engine was successfully started. The aircraft was taxied to the fuel-bay where it was refuelled to capacity with 252 litres of Avgas 100LL fuel. The instructor and student boarded the aircraft and no further starting problems were encountered.

At 1013Z, the aircraft took off from Runway 11 and headed for the Pretoria General Flying Training Area No.2. The aircraft reported at the Northern CTR boundary at 1023Z and was climbed to 8000 ft before the instructor commenced with single engine performance demonstrations. He pulled the mixture lever of the left-hand engine to the idle/cut-off position and the student commenced to secure the engine. According to the instructor, the student’s engine securing procedures were satisfactory and after completion, the engine re-start procedure was initiated approximately 2 minutes after it had been shut down.

After a number of unsuccessful attempts by the student to start the engine, the instructor attempted to start the engine but it was to no avail. The aircraft continued descending with the right-hand engine producing power and both the student and instructor were unable to re-start the left-hand engine. At that stage the instructor had already turned back towards Wonderboom aerodrome and was positioned at the northern boundary of the Roodeplaat dam. Due to the fact that the aircraft was not maintaining height, the instructor declared an emergency and decided to carry out a forced landing on a dirt road, approximately 7nm North East of Wonderboom in the Kameeldrift area. Approximately 80 m after touch down the aircraft collided with a fence and small bushes and veered off to the right. The aircraft continued veering off the road and collided with a sand embankment. The nose gear separated from the aircraft, which subsequently overturned and came to rest inverted. Although the aircraft was extensively damaged, both occupants vacated the aircraft with no injuries.

Probable Cause

During a simulated engine failure in order to demonstrate asymmetric flight and VMCA, the left-hand engine was shut down and failed to restart. The aircraft could not maintain altitude on the right-hand engine alone resulting in a forced landing on a dirt road. During the landing the aircraft collided with a fence and small bushes to the right of the road which caused it to veer off the right side of the road and overturn.

Jim’s Analysis

OK this is a tricky one. Would I happily sit in the back of the aeroplane while they were practicing single-engine work? Well if depends on how much confidence I had in the instructor. In this case – NO. Why so emphatic? Well, on the surface of it there is a bit of a question-mark hanging over the instructor.

How come he is 40 years old and only has a bit over 1000 hours? Did he start learning to fly in his late 30s? Or did he start early and simply not do much flying every year? Or something in between. I have no preferences either way – but I would still like to know why he has comparatively little experience for his age.

Next, and potentially much more worrying, is that he had less than five hours on type. Particularly if this happened to be his first twin, which we don’t know. That would mean that he would have been barely able to handle a genuine engine failure himself, let alone be teaching the procedures to someone else.

We don’t have any concrete answers for the above, but from the little we do know I would have declined a back seat.

From the evidence we have – I have to assume that, if this wasn’t the instructor’s first twin, then he was a bit thin on twin time. The reason for saying this is that new twin pilots always underestimate how much dead-engine cooling happens in those few of minutes that you are running on the other one.

At 8000 ft the outside air temperature could easily have been around zero, and even if it wasn’t – there is a hell of a lot of cooling air whipping away the heat from the cylinders. It still amazes me that you often have to go through the full cold-start procedure only a few minutes after the engine was shut down.

Those 180-hp Lycomings are not fuel injected and are very easy to start using three pumps of the throttle. I can only think the instructor was not familiar with the necessity of doing a cold-start. Particularly as the engines had been at normal operating temperatures only a short while earlier.

There are a couple more thoughts about why they were unable to start the dead engine. It is possible that the problem with starting the left engine on the ground was indeed a mechanical problem with the dual mag. And that it happened again in the air. But I think this is unlikely because the engine started twice on the ground after the AMO inspected had given it the OK.

Secondly, the method of shutting down the engine in the air, may not have been reversed for the restart. I am thinking that possibly the instructor switched off the fuel to simulate the engine failure, and the didn’t switch it on again. Or perhaps he pulled the mixture into idle-cutoff, and then left it there. It is easy to sit on the ground and think that would just be bloody stupid, but you need to be in a twin on one engine to observe the chaos in the cockpit – the six levers are all over the place and you have to think very carefully what should be where.

I have to confess that I have never had a problem starting an engine in the air. You set up everything, as if you were on the ground – remembering it is a cold start! And then you hit the starter and keep it there.

The engine will turn slowly at first and then as the prop starts to unfeather it will turn faster – until it is running. Set the pitch lever to mid range, otherwise the engine can temporarily overspeed when it suddenly becomes fully unfeathered. Also you should only set the throttle a little above idle, because you don’t want a cold engine producing a lot of power before it has warmed up.

With two up and fullish tanks, even if the OAT was +20°C he should have had a single engine ceiling of around 10,000 feet. There is no critical engine as they are counter-rotating. So I find it very strange that they were not able to get to Wonderboom at 4100 feet. Even a +30°C day would have given it a density altitude of just under 7000.

I suspect that many multi-engine pilots are not fully aware of the benefits of a small bank – less than 5° - into the live engine. It makes a massive difference to single-engine performance. Briefly, if you don’t bank into the operating engine, then the fuselage creates tremendous drag – because you are actually sideslipping. As soon as you use a little bank the aircraft is travelling in the direction it is pointing and you have got rid of all that drag.

I can offer you two memory aids – the first says “Ride on the Live”. So imagine yourself sitting on the live engine, or, tilting the aircraft towards the live engine. The other is “Raise the Dead”. Pretty self-explanatory – you raise the dead engine by banking away from it.

Finally, and I apologise in advance if I am being unfair to the pilot, because I don’t have sufficient information, but the aircraft stalls at 60 kt. If he had touched down on a road at this speed it seems unlikely that there would have been enough energy to run for 80 m and then get inverted. I have to guess that he landed, possibly flapless at an unnecessarily high speed.

What Can We Learn?

The main point of flying a twin is added safety. Unfortunately this is not free – it comes at the cost of the pilot being both comfortable, and current, with all the emergency procedures – in that particular aircraft.

If this pilot realised how poorly the aircraft performed on one engine, he may have conducted his simulated emergencies closer to the field.

I have to say that converting to your first twin often requires a whole change in attitude. You have to decide that now is the time to become a professional pilot, otherwise don’t do the conversion.

And it’s even a bigger step for instructors to teach their first few students multi engine emergencies. They have to be well on top of the situation and prepared for any mistakes that the student might make. So to finish, here are five quick tips for new multi-engine pilots:

Wake up and be professional – she is just waiting to bite you

Don’t do anything in a hurry after an engine failure

Remember that it only needs 5° of bank into the good engine to make it a good day

If you shut down an engine, make sure it is within easy single-engine reach of an airfield

If you shut down an engine – you have almost certainly got a cold-start on our hands.